1. Field of the Invention
The invention relates to a process and a measurement device for quantitatively detecting constituents of a pulp/fluid mixture for paper or cardboard production and a process of using the measurement device.
2. Background and Material Information
A number of conventional processes and measurement devices for quantitatively detecting constituents are described in "Wochenblatt fur Papierfabrikation", Paper Manufacturing Weekly, No. 7, 1996, pp. 272 to 279. According to the conventional processes and measurement devices, pulp consistency measurements (percentage of total mass) in a consistency range of 1.5% and higher have been carried out based upon shear force measurements and measurement of a dielectric constant over the propagation speed of microwaves. Pulp consistency measurements in the low consistency range below 1.5% are carried out, among other ways, based upon a depolarization measurement. Polarized light is conveyed through a pulp suspension, whereupon the polarized and depolarized portions in the measured light are compared to each other.
A measurement device is also described which, for various wavelengths, measures the depolarization of emitted laser light, the damping and backscattering of laser and xenon light, and the absorption of xenon light. As a result, fifteen different optical measurement values are registered simultaneously. The fibrous solids and filler consistencies are calculated from these measurement values. The obtained depolarization signal of the penetrating light is representative of the overall consistency. Damping and backscattering are used to determine the filler consistency and the overall consistency. This known measurement device is particularly useful for optimizing a wet section. This device is able to detect a number of different constituents of the mixture. However, it is relatively complicated and thus expensive. In addition, transmitted light is a prerequisite, which involves a greater space requirement. Further, the measurement conduit must have a small diameter, especially when the pulp consistency increases. At higher pulp consistencies, the medium must be diluted.
For measurements in the low consistency range, a known device utilizes the peak value measurement method with transmitted light, wherein fibers are counted by a focused light beam and the ash content is measured by absorption. This known device can distinguish ash and fibers as a group, but is incapable of further differentiation. Moreover, transmitted light is used, thus requiring additional space. Also, the measurement conduit must have a relatively small diameter, particularly when the pulp consistency increases. Finally, at higher pulp consistencies, the medium must be diluted.